A destacking device of the type mentioned in the introduction is required, in particular, for ice-cream production in which conically rolled comets or ice-cream wafers (referred to herein below as “cones” for short) are filled, in an ice-cream-filling machine, with the flavors of ice-cream envisaged therefore and are provided with suitable packaging. Known ice-cream-filling machines operate cyclically, in which case so-called trays each with six to twelve holders for cones are provided transversely to the running direction of the ice-cream-filling machine. The trays are processed simultaneously in one operation over the width of the six to twelve holders. In this case, the holders of a tray are first filled in each case with a conical wafer which is provided to receive and package the portion of ice cream which is to be produced. Six to twelve wafer cones then have to be carefully positioned at the same time in the conical packaging units. A chain conveyor then intermittently transports the tray with the six to twelve wafer cones and processes it further, in particular to fill the cones with one or more layers of the same or different flavors of ice-cream and then provides it with a closure cover.
Destacking devices are required for the abovementioned positioning of cones in the holders of a tray. Stacks of wafer cones inserted one inside the other are introduced manually in each case into the magazines of the destacking machine. From each stack, the lowermost cone then has to be separated and set down as carefully as possible in the associated holder of the tray which is to be filled. The performance requirements are at least around 30 to 60 cycles per minute and a reject rate (breakage) of less than or equal to one per thousand. Furthermore, the destacking device has to be capable of processing relatively large tolerances of the cones since these products are products made of natural ingredients which can also swell as a result of moisture absorption. For a cone top outer diameter of 42 mm, tolerances of ±2 mm typically are possible (with a cone length of approximately 105 mm).
As the cones are very fragile, the above-mentioned requirements are very difficult to achieve. Prior-art destacking devices available in the trade, for example, as described in U.S. Pat. No. 3,923,200, operate with rigid metallic grippers, which may comprise holding pins that retain the stack of cones and allow the lowermost end cone to drop when the tray holder is located beneath it. The gripping jaws are usually made of metal and protected by a soft material. In addition, the jaws have a small surface in contact with the wafer and they are not provided with a wafer or conical shape. In addition, they can present a hygienic risk. Also, the dropping action here results in a relatively high reject rate. Furthermore, there are problems with the centering of the cones in the holders. The motion of the grips is generally rotational and the mechanical assembly is rather complicated.
An alternative to rigid metallic jaws is proposed for Example in WO99/44479, which relates to a magazine for a dispenser for crisp fragile containers which comprises a tube with an elastically resilient membrane which is placed inside and whose internal volume is variable between a first position where it gently holds a wafer stack and a second position where it allows the free passage of the wafers through the tube for dispensing by blowing air between the tube and the membrane. From there, the wafers are taken over by jaws provided with resilient elements. This mechanism is of medium complexity and the reject rate is less.
In view of these disadvantages, improvements in such devices are desired and some particularly useful improvements are disclosed by the present invention.